This page was created for the purpose of giving an overview and an introduction to the basic terms:
“General workflow in After Effects”
The page introduces the basic terms and then links to pages that give incresingly deep detail.
I created this page to walk someone step by step through learning After Effects:
https://blogs.adobe.com/toddkopriva/2010/01/getting-started-with-after-eff.html
Regarding your Roto Brush question:
Watch this video tutorial and then work your way through the other resources linked to from here.
Roto Brush is not a beginner’s tool. It is an advanced and involved feature. I very strongly recommend against beginning your experience with After Effects with it. It was created to help people who already know how to do basic compositing work in After Effects.
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Todd Kopriva, Adobe Systems Incorporated
Technical Support for professional video software
After Effects Help & Support
Premiere Pro Help & Support
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